The present invention relates to image display devices having a plurality of electron beams each of which scans a different portion of the display and more particularly to systems for controlling each of the electron beams to obtain uniform brightness across the entire screen of the display.
Recently image display devices have been proposed having a plurality of modules each having its own electron beam for scanning a portion of the device screen. A device of this type is described in U.S. Patent Application Ser. No. 615,353 entitled "Guided Beam Flat Display Device" filed Sept. 22, 1975 by C. H. Anderson now U.S. Pat. No. 4,028,582. One of the problems encountered with such displays is that the brightness may vary from one portion of the screen to the next due to variations in the electron beam for that particular portion. For such devices to have practical use, the brightness of the display and hence the various electron beams must be relatively uniform.